The prevailing view about the organization of human foveal vision is that optic blur, photoreceptor sampling, and neural blur are all matched to each other. This project will scrutinize this view with laser interferometry, wave-front sensing, and adaptive optics. These technologies when combined allow the first quantitative measures of the eye's optics, cone mosaic, and neural response in the same individuals. Moreover, the use of adaptive optics allows any visual stimulus to be imaged on the retina at higher resolution than has previously been possible. We will explore the possibility that the neural visual system is not equipped to take advantage of all of the improvement in retinal image quality afforded by adaptive optics. We will test the hypothesis that improving the eye's optics leads to a degradation of performance on certain tasks such as vernier acuity and the identification of the color of small, brief flashes of light. Images of the trichromatic cone mosaic in living human eyes will be compared with maps of the color appearance of tiny flashes that stimulate single cones. These experiments will clarify the fundamental limits on spatial and color vision.